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[BFD, AArch64, x86] Improve warning for --force-bti
The AArch64 linker option to turn on BTI (--force-bti) warns in case there are input objects which have a missing GNU NOTE section for BTI. This patch is trying to improve the warnings that come out. In order to do so, I propose adding a new argument to elf_merge_gnu_properties and the backend function merge_gnu_properties. This new argument makes sure that we now pass both the objects along with the properties to which they belong to. The x86 backend function has also been updated to match this change. *** bfd/ChangeLog *** 2019-03-21 Sudakshina Das <sudi.das@arm.com> * elf-bfd.h (struct elf_backend_data): Add argument to merge_gnu_properties. * elf-properties.c (elf_merge_gnu_properties): Add argument to itself and while calling bed->merge_gnu_properties. (elf_merge_gnu_property_list): Update the calls for elf_merge_gnu_properties. * elfnn-aarch64.c (elfNN_aarch64_merge_gnu_properties): Update handling of --force-bti warning and add argument. * elfxx-aarch64.c (_bfd_aarch64_elf_link_setup_gnu_properties): Add warning. * elfxx-x86.c (_bfd_x86_elf_merge_gnu_properties): Add argument. * elfxx-x86.h (_bfd_x86_elf_merge_gnu_properties): Likewise in declaration. *** ld/ChangeLog *** 2019-03-21 Sudakshina Das <sudi.das@arm.com> * testsuite/ld-aarch64/aarch64-elf.exp: Add new test. * testsuite/ld-aarch64/bti-plt-1.s: Add .ifdef for PAC note section. * testsuite/ld-aarch64/bti-plt-6.d: Update warning. * testsuite/ld-aarch64/bti-plt-7.d: Likewise. * testsuite/ld-aarch64/bti-warn.d: New test.
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‎bfd/ChangeLog‎

Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1,3 +1,19 @@
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2019-03-21 Sudakshina Das <sudi.das@arm.com>
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* elf-bfd.h (struct elf_backend_data): Add argument to
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merge_gnu_properties.
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* elf-properties.c (elf_merge_gnu_properties): Add argument to
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itself and while calling bed->merge_gnu_properties.
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(elf_merge_gnu_property_list): Update the calls for
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elf_merge_gnu_properties.
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* elfnn-aarch64.c (elfNN_aarch64_merge_gnu_properties): Update handling
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of --force-bti warning and add argument.
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* elfxx-aarch64.c (_bfd_aarch64_elf_link_setup_gnu_properties): Add
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warning.
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* elfxx-x86.c (_bfd_x86_elf_merge_gnu_properties): Add argument.
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* elfxx-x86.h (_bfd_x86_elf_merge_gnu_properties): Likewise in
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declaration.
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2019-03-20 Sudakshina Das <sudi.das@arm.com>
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* elfxx-aarch64.c (_bfd_aarch64_elf_link_fixup_gnu_properties): Define.

‎bfd/elf-bfd.h‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1473,7 +1473,7 @@ struct elf_backend_data
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unsigned int);
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/* Merge GNU properties. Return TRUE if property is updated. */
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bfd_boolean (*merge_gnu_properties) (struct bfd_link_info *, bfd *,
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bfd_boolean (*merge_gnu_properties) (struct bfd_link_info *, bfd *, bfd *,
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elf_property *, elf_property *);
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14791479
/* Set up GNU properties. */

‎bfd/elf-properties.c‎

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -198,7 +198,7 @@ _bfd_elf_parse_gnu_properties (bfd *abfd, Elf_Internal_Note *note)
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with ABFD. */
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static bfd_boolean
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elf_merge_gnu_properties (struct bfd_link_info *info, bfd *abfd,
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elf_merge_gnu_properties (struct bfd_link_info *info, bfd *abfd, bfd *bbfd,
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elf_property *aprop, elf_property *bprop)
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{
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const struct elf_backend_data *bed = get_elf_backend_data (abfd);
@@ -207,7 +207,7 @@ elf_merge_gnu_properties (struct bfd_link_info *info, bfd *abfd,
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if (bed->merge_gnu_properties != NULL
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&& pr_type >= GNU_PROPERTY_LOPROC
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&& pr_type < GNU_PROPERTY_LOUSER)
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return bed->merge_gnu_properties (info, abfd, aprop, bprop);
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return bed->merge_gnu_properties (info, abfd, bbfd, aprop, bprop);
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switch (pr_type)
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{
@@ -289,7 +289,7 @@ elf_merge_gnu_property_list (struct bfd_link_info *info, bfd *first_pbfd,
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TRUE);
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/* Pass NULL to elf_merge_gnu_properties for the property which
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isn't on *LISTP. */
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elf_merge_gnu_properties (info, first_pbfd, &p->property, pr);
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elf_merge_gnu_properties (info, first_pbfd, abfd, &p->property, pr);
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if (p->property.pr_kind == property_remove)
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{
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if (info->has_map_file)
@@ -365,7 +365,7 @@ elf_merge_gnu_property_list (struct bfd_link_info *info, bfd *first_pbfd,
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else
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number_p = FALSE;
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if (elf_merge_gnu_properties (info, first_pbfd, NULL, &p->property))
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if (elf_merge_gnu_properties (info, first_pbfd, abfd, NULL, &p->property))
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{
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if (p->property.pr_type == GNU_PROPERTY_NO_COPY_ON_PROTECTED)
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elf_has_no_copy_on_protected (first_pbfd) = TRUE;

‎bfd/elfnn-aarch64.c‎

Lines changed: 17 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -9968,7 +9968,7 @@ elfNN_aarch64_link_setup_gnu_properties (struct bfd_link_info *info)
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for the effect of GNU properties of the output_bfd. */
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static bfd_boolean
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elfNN_aarch64_merge_gnu_properties (struct bfd_link_info *info,
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bfd *abfd,
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bfd *abfd, bfd *bbfd,
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elf_property *aprop,
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elf_property *bprop)
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{
@@ -9977,17 +9977,26 @@ elfNN_aarch64_merge_gnu_properties (struct bfd_link_info *info,
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/* If output has been marked with BTI using command line argument, give out
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warning if necessary. */
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if ((prop & GNU_PROPERTY_AARCH64_FEATURE_1_BTI)
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/* Properties are merged per type, hence only check for warnings when merging
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GNU_PROPERTY_AARCH64_FEATURE_1_AND. */
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if (((aprop && aprop->pr_type == GNU_PROPERTY_AARCH64_FEATURE_1_AND)
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|| (bprop && bprop->pr_type == GNU_PROPERTY_AARCH64_FEATURE_1_AND))
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&& (prop & GNU_PROPERTY_AARCH64_FEATURE_1_BTI)
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&& (!elf_aarch64_tdata (info->output_bfd)->no_bti_warn))
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{
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if ((aprop && !(aprop->u.number & GNU_PROPERTY_AARCH64_FEATURE_1_BTI))
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|| (bprop && !(bprop->u.number & GNU_PROPERTY_AARCH64_FEATURE_1_BTI))
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/* If either property is NULL, it means its bfd did not have any
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property. */
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|| !aprop || !bprop)
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|| !aprop)
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{
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_bfd_error_handler (_("warning: BTI turned on by --force-bti when "
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"all inputs do not have BTI in NOTE section."));
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_bfd_error_handler (_("%pB: warning: BTI turned on by --force-bti when "
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"all inputs do not have BTI in NOTE section."),
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abfd);
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}
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if ((bprop && !(bprop->u.number & GNU_PROPERTY_AARCH64_FEATURE_1_BTI))
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|| !bprop)
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{
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_bfd_error_handler (_("%pB: warning: BTI turned on by --force-bti when "
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"all inputs do not have BTI in NOTE section."),
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bbfd);
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}
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}
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‎bfd/elfxx-aarch64.c‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -719,6 +719,11 @@ _bfd_aarch64_elf_link_setup_gnu_properties (struct bfd_link_info *info,
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prop = _bfd_elf_get_property (ebfd,
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GNU_PROPERTY_AARCH64_FEATURE_1_AND,
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4);
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if (gnu_prop & GNU_PROPERTY_AARCH64_FEATURE_1_BTI
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&& !(prop->u.number & GNU_PROPERTY_AARCH64_FEATURE_1_BTI))
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_bfd_error_handler (_("%pB: warning: BTI turned on by --force-bti "
725+
"when all inputs do not have BTI in NOTE "
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"section."), ebfd);
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prop->u.number |= gnu_prop;
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prop->pr_kind = property_number;
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‎bfd/elfxx-x86.c‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2401,6 +2401,7 @@ _bfd_x86_elf_parse_gnu_properties (bfd *abfd, unsigned int type,
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bfd_boolean
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_bfd_x86_elf_merge_gnu_properties (struct bfd_link_info *info,
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bfd *abfd ATTRIBUTE_UNUSED,
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bfd *bbfd ATTRIBUTE_UNUSED,
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elf_property *aprop,
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elf_property *bprop)
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{

‎bfd/elfxx-x86.h‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -691,7 +691,7 @@ extern enum elf_property_kind _bfd_x86_elf_parse_gnu_properties
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(bfd *, unsigned int, bfd_byte *, unsigned int);
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extern bfd_boolean _bfd_x86_elf_merge_gnu_properties
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(struct bfd_link_info *, bfd *, elf_property *, elf_property *);
694+
(struct bfd_link_info *, bfd *, bfd *, elf_property *, elf_property *);
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696696
extern void _bfd_x86_elf_link_fixup_gnu_properties
697697
(struct bfd_link_info *, elf_property_list **);

‎ld/ChangeLog‎

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1,3 +1,11 @@
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2019-03-21 Sudakshina Das <sudi.das@arm.com>
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* testsuite/ld-aarch64/aarch64-elf.exp: Add new test.
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* testsuite/ld-aarch64/bti-plt-1.s: Add .ifdef for PAC note section.
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* testsuite/ld-aarch64/bti-plt-6.d: Update warning.
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* testsuite/ld-aarch64/bti-plt-7.d: Likewise.
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* testsuite/ld-aarch64/bti-warn.d: New test.
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19
2019-03-21 Alan Modra <amodra@gmail.com>
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* testsuite/ld-elf/fini2.s: Reduce alignment.

‎ld/testsuite/ld-aarch64/aarch64-elf.exp‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -407,3 +407,5 @@ run_dump_test "pac-plt-1"
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run_dump_test "pac-plt-2"
408408
run_dump_test "bti-pac-plt-1"
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run_dump_test "bti-pac-plt-2"
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411+
run_dump_test "bti-warn"

‎ld/testsuite/ld-aarch64/bti-plt-1.s‎

Lines changed: 17 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -21,3 +21,20 @@ _start:
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.p2align 3
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5:
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.endif
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.ifdef __property_pac__
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.section ".note.gnu.property", "a"
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.p2align 3
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.long 1f - 0f /* name length */
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.long 5f - 2f /* data length */
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.long 5 /* note type */
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0: .asciz "GNU" /* vendor name */
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1:
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.p2align 3
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2: .long 0xc0000000 /* pr_type. */
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.long 4f - 3f /* pr_datasz. */
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3:
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.long 0x2 /* PAC. */
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4:
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.p2align 3
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5:
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.endif

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